The independent commission's statement on Monday brought the total number of officers awaiting trial to four. They include Constable Collis Brown, who was arrested in March and faces three counts of murder, and Corporal Kevin Adams, who is alleged to have killed four men between 2011 and 2013.

The Jamaica Constabulary Force said that police had been cooperating with the commission "since the beginning of these investigations".

An independent commission has been created to investigate the rising number of killings by police

At a news conference in the capital Kingston, Comissioner Terrence Williams said there was reason to believe that the killings, which were initially reported as unsolved, were "police-involved homicides". His agency suspects other unsolved deaths involving civilian gunmen could have actually involved police officers, the Associated Press reported.

Investigators are asking the public to provide information about eight other incidents that resulted in the deaths of nine people, including a case where a hospitalised man was killed by a masked assailant.

Williams said investigators are reviewing cases across the Carribbean nation of 2.7 million people, particularly when there is a pattern of officers being involved in more than one shooting fatality.

Accusations of extra-judicial killings by police are rife in Jamaica, with human rights organisations warning of a culture of impunity among police officers. Residents of mostly poor neighbourhoods regularly protest what they say are unjustified killings by security forces.

Last year, 258 civilians were killed by the police and there were 2,200 fatal shootings by security forces between 2000 and 2010.

Only two police officers have been convicted of involvement in wrongful killings.